This invention relates to improved cross wound flat filament yarn packages and means for their production in melt spinning processes in which the improved package has a specific type of compact pile bunch wound thereon. More specifically, this invention is directed to an improved traverse roll which can be used to provide crosswound packages.
Cross wound packages of melt spun yarn are extremely old in the art. "Melt spinning" has been defined as "(t)he process in which the fiber-forming substance is melted and extruded into air or other gas, or into a suitable liquid, where it is cooled and solidified, as in the manufacture of polyester or nylon." (see "Man-Made Fiber and Textile Dictionary,", 1978, Celanese Corporation.)
Conventionally, these packages have been doffed, and the empty tubes donned, by operators. More recently, there has been an attempted trend to the use of semiautomated equipment in which machines rather than human operators perform the doffing/donning operations and subsequent handling of the packages.
The trailing yarn end on the outside of prior art melt spun cross wound packages is very prone to accidental unwinding. This is particularly so during doffing from a high speed winding machine in which the package is surface driven, because windage due to the driven rolls tends to unwind the trailing end as the package slows down and comes to rest. Trailing ends that unwind and entangle equipment pose problems particularly in the development of automated processes.
Cross wound packages having various types of pile windings thereon to prevent accidental unwinding by gravity during subsequent handling are known in the art. In particular, German Pat. No. 296,203 (published 1917) discloses a "plowed pile winding" and French Pat. No. 2,312,446 (published 1976) discloses a "radially compressed hand knitting yarn overlapped pile winding", as discussed below.
German Pat. No. 296,203 describes the production of a compacted pile wound bunch on the surface of a cross wound shuttle pirn in old fashioned slow speed embroidery equipment. Essentially, a pair of guides ("nose" and "horn") are pressed against the package during the pile winding. The nose prevents displacement of the thread as it runs onto the bobbin. The horn acts as a plow and lifts the windings already on the bobbin over the winding just applied. Thus the pile winding may be classified as a "plowed pile winding". Such a device would appear to be effective only with heavy denier yarns (such as embroidery yarns); and at tensions sufficiently low to permit the horn to dig under the windings; and at speeds sufficiently low to prevent the horn from damaging the yarn.
French Pat. No. 2,312,446 teaches process and apparatus
"which allows the making of balls the free end of the thread of which less easily runs the risk of unwinding. PA1 The solution of this problem provided according to the present invention consists in that towards the end of the winding process the thread is guided in a fixed way with respect to the longitudinal direction of the winding cylinder between the positioning mechanism and the winding cylinder and in that, thanks to this guiding of the thread and in spite of the traversing movement of the positioning mechanism, the end of the thread is wound onto the ball essentially in a single plane extending transversely to the longitudinal direction of the winding cylinder. PA1 (1) a package of melt spun yarn; PA1 (2) accidental non-gravity unwinding of the package, while it is still on the winder, as a package is rapidly stopped rotating from speeds of 3000 mpm under conditions of high air turbulence; PA1 (3) accidental unwinding of the package when the axis of the package is essentially horizontal rather than vertical; PA1 (4) packages of (2) in which the drive of the package also pulls the melt spun filaments away from the spinneret; PA1 (5) packages which, when freshly wound, have a temperature greater than the ambient temperature; PA1 (6) packages in which the yarn is untwisted interlaced continuous multifilament yarn; PA1 (7) packages of flat melt spun yarn in which the upstream pile turns partly underlay the downstream pile turns; PA1 (8) packages that are surface-driven by a separate drive roll; PA1 (9) any definition of the minimum number of pile windings; PA1 (10) any definition of the maximum unwinding tension; PA1 (11) packages in which the denier and dye uptake of the resultant yarn are dependent upon winding conditions such as yarn tension and wind-up speed; and PA1 (12) packages in which the pile turns are wound at controlled high tension of at least 0.5 g/dtex. PA1 1. yarn is interlaced continuous multifilament yarn; PA1 2. package having been decellerated to rest from a surface speed of at least 3,000 mpm within 20 seconds and having an absence of broken filaments; PA1 3. package having been cooled to ambient temperature after being wound; PA1 4. package has a void space between the filaments of less than 40 percent by volume; often less than 35 percent and sometimes less than 30 percent; PA1 5. yarn of the cross wound turns have essentially the same denier and dye uptake; PA1 6. yarn having weight of less than 300 decitex; PA1 7. yarn having zero real twist package may be saddle-shaped; and PA1 8. yarn may be spun, partially oriented or fully drawn in a wide range of deniers and numbers of filaments.
This offers the advantage that the last turns of the thread on the ball are placed very close to one another and partly overlap so as to be protected to a large extent against the risk of unwinding.
It is an advantage within the framework of the process according to the invention that, after initiating the guiding of the thread according to the invention, the winding cylinder rotates more slowly than during the normal winding of the thread without the guiding envisaged according to the invention. Desirably the end of the thread is wound onto the central zone of the ball. In this way the end of the thread is always in a well determined plane which can be covered, for example, by a tape so that the end of the thread is always held securely by this latter."
"Ball" is defined elsewhere as "(t)he form of knitting yarn ready for use. It may be made of yarn from any of the major fibers, alone or in combination. The yarn is sold in so many ounce balls to the consumer." ("The Modern Textile Dictionary" by George E. Linton, published in 1957 by Duell, Sloan and Pierce). Likewise, "ball winding machine" is defined "(t)his machine winds yarn into small ball packages. Yarns for knitting, crocheting, tatting, etc., are wound this way." Accordingly, the term "ball" relates essentially to a small package of hand knitting yarn. Further, balls are normally made by a rewinding process in which the yarn on the ball is not "flat continuous filament yarn", but rather bulky yarns wound at tensions insufficient to remove the bulk.
All the thread shown in the figures of the French '446 patent is twisted and therefore typically compressible in cross-section. Accordingly, the pile winding may be classified as a "radially compressed hand knitting yarn overlapped pile winding".
Neither of the foregoing patents relates specifically to the following:
The trailing end of sewing thread sold for domestic use is typically held in a slot of the tube or spool flange. The compact side-by-side winding generally renders it quite impossible to embed the trailing end by hand between two adjacent windings. Likewise it is extremely difficult, if not impossible, to rewind sewing thread by hand in any type of wind, without tying a knot (such as a highwayman's hitch knot) that permits the trailing end to be secured.
Further, cross wound packages of melt spun flat filament yarn made by existing high speed melt spinning processes typically inherently have properties including the following:
Nowhere does the prior appear to disclose or suggest a cross wound package of melt spun flat filament yarn characterized by the yarn's outer end being pile wound in a compact bunch on the cross wound package's surface, the yarn end comprising at least twenty pile turns, the pile turns comprising upstream pile turns and downstream pile turns, and wherein the upstream pile turns partly underlap the downstream pile turns.